The purpose of the proposed research is to identify and investigate processes involved in the formation and maintenance of retinal adhesion. Intimate contact between the neural retina and the retinal pigment epithelium is essential for nourishment of the outer retina (via the choroidal circulation) and for phagocytosis and degradation of shed photoreceptor outer segments. I propose to examine possible biochemical factors responsible for development of retinal adhesion in the embryonic eye and for its maintenance in the adult eye. Cell surface glycoproteins have been implicated in several cell recognition processes which accompany embryonic tissue adhesion and differentiation (e.g., retina and palate formation). Therefore, one approach will be to examine glycoprotein production in the embryonic chick eye, in which firm retinal attachment occurs at day 17 of development. This will be accomplished through (1) Measurement of L-glutamine-D-fructose-6-phosphate aminotransferase (required for glycoprotein synthesis) in developing ocular tissues, and (2) Examination of the production of radioactively labelled glycoproteins. An inquiry into the role of glycoproteins in retinal adhesion in the adult eye will be initiated by examination of glycoproteins in the interphotoreceptor matrix of the bovine eye. These molecules will be fractionated and characterized by gel electrophoresis and affinity (lectin) chromatography. Their effect upon retinal adhesion will be measured in a cell aggregation assay with epithelial cells and rod outer segments. Glycoproteins isolated from pigment epithelium and photoreceptor cell plasma membranes will be studied for their effect upon cell adhesion and for their physicochemical interactions with one another. I propose also to investigate whether fluid transport out of the interphotoreceptor space is involved in the maintenance of retinal attachment in the adult and, if so, what types of active transport pumps may be responsible. The long-range objective is to apply the results to the prevention and treatment of retinal detachment.